Down the Garden Path

Richard Hentschel, Extension Educator

Master Gardeners receive calls over the phone and visits to the office about growing vegetables in a raised bed frequently from gardeners that have experienced bad luck growing in a traditional garden bed and wonder if a raised bed will change the color of their thumb from a brown to a green again. Raised beds have some added benefits but not necessarily advantages over growing in the ground. Water drainage is one of those benefits. You certainly have drainage normally, yet a raised bed will drain away the excessive moisture quicker after a heavy rain. The sooner the soil drains, the less likelihood of our vegetable root systems suffering from a lack of soil oxygen. Additionally, diseases that favor wet waterlogged soils are less likely to be a problem.

Another benefit is that a raised bed has soil that will warm up sooner in the spring, allowing the ambitious gardener to get the first plantings in a few days earlier regardless of the kind of vegetable grown. Remember when the neighbor made those small mounds to plant the cucumber or pumpkin seed? This is a simple way to create a bit of soil that is warmer sooner to get those warm loving seeds up and out of the ground. You can think of that but doing it for your full garden.

Another follow up question about raised beds is the one about what kind of soil should be used. To maximize the drainage potential, gardeners have the opportunity to take care of that when they are filling the raised bed. If your natural soil in the yard is heavy, contains a lot of clay, that is not what you want to fill the bed with. That heavy soil may be a component mixed with good quality black dirt and a source of organic matter.

Organic matter serves several functions in the bed. A soil with lots of organic matter will retain moisture between your watering or natural rain. Organic matter provides soil structure for all the important spaces that contain that soil oxygen that roots will use to actively move nutrients and water into the above ground plant parts. Organic matter by its nature breaks down with time, releasing nutrients that every vegetable plant needs. Vegetable plants use these throughout the growing season and this release is an ongoing process, allowing the vegetable plants to get what they need when they need it. Lastly, organic matter is acidic and helps maintain the soil pH where plants thrive. Just like your in ground garden beds, a soil test should be done every few years to be sure your pH and nutrient ion levels are adequate.

A simple way to try out a raised bed before committing to building a permanent one is to use the soil that would otherwise be between your rows and create raised rows that way. When you are done, you still have your walkways but your rows are now several inches taller and perhaps wider as well. The season is just getting underway and there is plenty of time and vegetables to sow for the remainder of the summer and right into fall.